King's Tower takes any hero. Each faction tower only lets in heroes of its faction, and higher floors in every tower ask for two or three teams at once, with a hero who wins one fight locked out of the rest of that floor.
King's TowerAny hero, 3,300 floors, two teams from floor 701, three from 951Tower of LightLightbearers only, 1,950 floors, two teams from floor 451, three from 661Brutal CitadelMaulers only, 1,950 floors, two teams from floor 451, three from 661World TreeWilders only, 1,950 floors, two teams from floor 451, three from 661Forsaken NecropolisGraveborn only, 1,950 floors, two teams from floor 451, three from 661Celestial SanctumCelestials only, 1,300 floors, two teams from floor 351Infernal FortressHypogeans only, 1,300 floors, two teams from floor 351